The proposed research will explore the mechanisms and adaptive significance of multiple sensory control of social behavior in the African mormyrid fish. Weakly electric fish, whose behavior has been studied by the P.I. in the field and laboratory were chosen because both their locomotor and electric discharge behavior are influenced by multiple sensory modalities renderiing them excellent study objects for the investigation of multisensory integration. Five interrelated projects are proposed: (1) a long-term laboratory study on social interaction (aggregation, schooling, spacing, dominance); (2) a field project on ethological and ecological aspects of sympatric mormyrid populations in Lake Kainji, Nigeria; (3) a laboratory study on the effect of water conductivity on the fish's electrolocation and e-communication fields; (4) an investigation of the fish's circadian rhythmicity and possible zeitgebers (light, temperature, conductivity); and (5) a study of dyadic social interactions. By manipulating the fish's sensory environment and/or, whenever possible reversibly interfering with selective aspects of the fish's sensory system, we will investigate the behavioral evidence for multisensory integration such as cross-modal transfer, sensory equivalence, and sensory interdependence and discuss the applicability and relevance of our approach to other levels of phyletic organization.